DENVER — A 19-year-old man was sentenced to 40 years in prison Friday in connection with a 2020 house fire that killed a Senegalese family in Denver’s Green Valley Ranch neighborhood.

Gavin Seymour pleaded guilty to second-degree murder in January 2024. He faced between 16 and 40 years in prison on the single count. Dozens of other charges were dismissed as part of the plea agreement.

The fire was reported in the early hours of Aug. 5, 2020, along the 5300 block of N. Truckee Street. Later that day, the Denver Fire Department confirmed a toddler, child, and three adults had died — later identified as Djibril and Adja Diol, their 2-year-old daughter Khadija, Hassan Diol and her infant daughter, Hawa Baye — and investigators suspected arson. The family had immigrated to Colorado from Senegal.

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Authorities focused on identifying three masked people seen on surveillance footage in the area at the time of the fire.

Evidence showed the fire was started with gasoline and surveillance video depicted one of teens carrying a jug to the scene, according to an arrest affidavit. It also showed that the suspects entered the home at some point and gasoline was put on the interior walls on the first floor of the home, according to the affidavit.

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About half a year after the deadly fire, in late January 2021, authorities arrested three teens in connection with the crime: Seymour and Kevin Bui, both 16 years old at the time of their arrest, and Dillon Siebert, who was 15 at the time of his arrest. The trio incorrectly thought Bui’s stolen iPhone was inside the home, according to an arrest affidavit, and went to the home to retaliate. No evidence has been found to show the Diol family had anything to do with the alleged theft of the phone.

During his sentencing Friday, Seymour apologized for his actions in the fire and said he would trade places with the victims if he could. His parents asked the judge for leniency, and case workers who have interacted with him while incarcerated described him as remorseful and working to better himself while behind bars.

Shane Seymour, Gavin Seymour’s father, told the judge Gavin is “not the monster he’s portrayed to be.”

But loved ones of the Diol family described the agony and fear they and the broader Senegalese community have lived with since the incident. They asked the judge to hand down the maximum sentence, while also saying it did not constitute justice.

“If I could get the death penalty or life sentence, that’s what would be justice,” said Amadou Beye, whose wife and daughter were killed in the fire. “That’s what justice would look like for me. But since 40 years is all we could have, what I could get for my family, I’m just gonna deal with it.”

While Seymour was sentenced to 40 years in prison, the prosecutor noted he would be allowed to apply for early parole after serving 20 years under Colorado law since the crime occurred while he was a juvenile. Loved ones of the victims would be alerted in that case.

Bui pleaded not guilty to the charges against him in August 2022. He has an arraignment scheduled for March 21 in connection with this case. He also faces charges tied to allegedly possessing and distributing pills with suspected fentanyl in jail.

Siebert took a plea deal in December 2022 and pleaded guilty to second-degree murder, including a sentence enhancer for using a weapon in a crime. In February 2023, he was sentenced to seven years in district court and three years in juvenile court, for a total of 10 years behind bars.